High power gas and solid state lasers have gained acceptance in manufacturing today by reducing costs and improving product quality. The utilization of such lasers as a percentage of the time they are available for use is, however, low. This is the case since, typically, such applications are set up on a one laser per workstation basis. As a result, these applications experience a high set-up to process time ratio and a large capital cost per workstation.
A design objective of such laser workstations is to provide flexibility by applying the beam generated by a single power laser, e.g. to effect a weld, at a plurality of physically different locations and thereby improve laser utilization. One technique known in the art for providing such flexibility is to direct the power laser beam through one end of an optical fiber so that the other end of the fiber may be moved between a plurality of different locations on a workpiece. Apparatus for the practice of such a technique is disclosed in U.S. Pat. No. 4,564,736. A second technique known in the art for providing such flexibility is to divert a power laser beam among different points on a workpiece and/or between workstations by means of mirrors and refracting elements. Typically, the total distance that the beam of a commercially available rod laser can travel, before diverging to an unusable size, is small (e.g. less than 2 meters). Thus, the total number of workstations among which a laser beam can be diverted is greatly limited by the total distance the beam can travel. As a result, the improvement in laser utilization achievable by diverting the laser beam in this fashion is limited. A third technique known in the art to increase flexibility of laser use is to split the power laser beam into multiple portions each of which is diverted to a different work location. A substantial drawback to this technique is the reduced laser power, caused by the beam splitting, delivered to each work location.
While the above-described techniques are intended to improve laser utilization, the capital cost of the system equipment required to implement such techniques is substantial. In the context of power laser utilization, it is therefore important to safeguard the substantial investment in such system equipment against damage caused by misdirection or scattering of the power laser beam. Such misdirection or scattering may, for example, simply be caused by the failure of a beam diverting component of the system, such as a mirror or refracting element that shatters or slips on its mounting. The component failure must be promptly sensed and appropriate action taken to obviate or minimize damage that can otherwise result.
With respect to component failures in such systems, a second consideration of equal importance is maintenance of a safe work environment for personnel attending the laser system. It is highly undesirable to have the power laser beam misdirected or scattered due to a component failure where injury to personnel in the vicinity may result. One solution to the personnel safety problem is to maintain the entire system in a Class I enclosure, as defined by ANSI Standard Z136.1, an enclosure classification well known in the art. One drawback to this solution is the resulting inaccessibility of system components to the attending personnel. A second drawback is the additional cost incurred to construct the Class I enclosure. It is further noted that this solution does nothing to minimize equipment damage in the case of component failure.
A different system for improving laser utilization, described hereinbelow and in copending U.S. patent application Ser. No. 944,771 filing date 12-22-86, enables the full power of a single power laser to be injected into a plurality of optical fibers for transmission to remote workstation locations. It is therefore a principal object of the present invention to provide such a system for improving laser utilization that is further adapted to minimize damage to its components and injury to attending personnel in the case of a component failure.